Now, one of the interesting things that happened is, that at certain periods, as the climate changed, people were moved up into the northeastern part of Africa where more changes occurred, and then as the climate changed you can imagine there would be pressure to move outward, away from the climactic change and it is thought, that in fact that, caused people to move out of Africa across this sort of bridge between Eurasia and Africa. And there are really two exits, one across the Horn of Africa and the southern part of the Arabian peninsula and the other across the Sinai. Now one thought is that there was a very early out of Africa migration about 60,000 to 70,000 years ago that hugged the coast and went down through Indonesia, Papua, New Guinea, and down into Australia and the Australian aboriginals are in fact the descendants of that migration. Then it's very clear that a population here in this region of the world gave rise to certain distinctive lineages of mitochondrial DNA, which then in fact, were able to leave Africa and colonize Europe and Asia.